Point take-off and landing (PTOL) relates to the capabilities of unmanned aerial vehicles (UAVs) and other aircrafts to perform take-off and landing operations without a runway at a confined location. In today's high spending UAV military market, there is a lack of good solutions for enabling PTOL of UAVs. One specific example is the recovery of large-wingspan fixed-wing UAVs onto moving vehicles on land or on water. The large wingspans of these UAVs complicates the ability to land onto a ship or similar aquatic vessel, which may be subject to large amplitude and rapid angular movements along its roll, pitch and yaw axes. The difficulty for safe UAV landing may be further exacerbated by the ship's masts and antennas and by the turbulence behind the ship superstructure. Besides the lack of a runway, PTOL of a UAV onto (or from) a land vehicle may also be complicated by the presence of obstacles in the vicinity of the vehicle, by strong winds, and by darkness or low-visibility weather conditions.
The need for UAV recovery onto a ship has a long history. In 1985, Floyd Kennedy of the AIL Corporation discussed the need for fleet-integral UAVs to provide Airborne Early Warning (AEW) to U.S. Navy non-aviation task forces. The solution was observed to lie with fixed-wing UAVs due to their endurance capabilities, raising issues for point landing of such UAVs onto small ships (i.e., non-aircraft carriers), such as the concern that their long wings may interfere with the ship deck elements. Especially noteworthy is the U.S. Congress defined requirement for “Endurance Category” UAVs (i.e., which are capable of remaining airborne for long durations) for U.S. Navy ships, in the first “UAV Masterplan” of 1988, although no such system appears to have been deployed as of yet. One problem is that fixed-wing UAVs and other similar flying objects cannot hover like a helicopter while connecting to a ship's cable, so the U.S. Navy's RAST (Recovery Assist & Transfer) system solution for helicopters cannot be used. Additionally there is a need to cope with turbulence behind the ship's superstructure, wind-over-deck from all directions and at various intensities, and darkness or low-visibility weather conditions.
U.S. Pat. No. 7,219,856 to Watts, entitled “UAV recovery system” discloses an embodiment where a UAV system is coupled to the deck of a sea faring vessel. The UAV capture system includes a single arresting line that is supported by a stanchion, which may be disposed on a rotatable boom. The UAV hooks onto the line and is abruptly stopped in flight and once stopped it appears to be left hanging, which may cause damage to the UAV.
Australian Patent Application No. 2009200804 to Kariv, entitled “An unmanned aerial vehicle launching and landing system” discloses an embodiment relating to a system for landing UAVs. The system comprises an arm based structure and an axis means installed along the arm of the structure, enabling the arm to move around it. The arm is propelled into rotational motion around the axis from the instant that the UAV connects to landing arm. It appears that the rotational momentum of UAVs, especially heavier ones, may apply a taxing force onto the rotational axis.